Multi-Extrusion Head with Elastic Sleeve for Blow Molding
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Solution Overview
Problem
Existing blow molding systems face challenges in dynamically profiling the die gap in the circumferential direction, especially in cramped installation conditions, which limits the production of complex container shapes with uniform wall thickness.
Innovation Solution
A method using a multiple extrusion head with program-controlled individual drives and transmission elements acting on elastically deformable sleeves to dynamically control melt distribution in the circumferential direction, allowing for independent force application and deformation of the sleeves, even with tight spacing between extrusion tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electric actuators are installed in the mold parting plane to adjust the nozzle gap, then the melt distribution in the circumferential direction can be optimized, but the installation space requirements cannot be met when stitch spacing is small
Solution Approach 1:
The patent introduces an elastically deformable sleeve as an intermediary component between the actuator and the die gap. The actuator applies force to the sleeve, which then deforms elastically to adjust the die gap geometry. This intermediary allows the system to achieve the desired melt distribution control without requiring direct installation of actuators in the constrained mold parting plane area.
Solution Approach 2:
The patent employs an elastically deformable sleeve that can be deformed by program-controlled power drives to change the die gap geometry dynamically during extrusion. This flexible component allows for precise control of melt distribution in the circumferential direction without requiring rigid actuator installation in cramped spaces, as the sleeve can be actuated from positions outside the immediate die gap area.
2Manufacturing precision
If the die gap geometry is changed dynamically during extrusion to produce complex container shapes, then the wall thickness uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent makes the die gap geometry dynamic by introducing elastically deformable sleeves that can be adjusted during the extrusion process. The sleeves are deformed by program-controlled power drives to change the die gap profile in real-time, allowing the production of complex container shapes with uniform wall thickness. This dynamic adjustment capability enables precise control over preform geometry without requiring multiple fixed tools.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with program-controlled power drives that act on elastically deformable sleeves. Instead of using multiple rigid mechanical components to achieve geometry changes, the system uses controlled elastic deformation of sleeves, simplifying the overall mechanical structure while maintaining the ability to produce complex shapes with precise wall thickness control.
3Productivity
If multiple extrusion tools are arranged in a row with small stitch spacing, then the productivity is improved, but the installation of adjustment mechanisms becomes difficult
Solution Approach 1:
The patent places the elastically deformable sleeve inside the die structure, nesting the adjustment mechanism within the existing tool geometry. The sleeve is positioned within the die gap area and can be actuated by power drives located outside the immediate tool head, allowing compact arrangement of multiple extrusion tools in a row with small stitch spacing while maintaining full adjustment capability.
Solution Approach 2:
The elastically deformable sleeve serves as an intermediary that transmits force from actuators positioned outside the cramped installation space to the die gap. This allows the adjustment mechanisms to be located in more accessible positions while still achieving precise control of the die gap geometry, facilitating easier installation and maintenance in high-productivity configurations with multiple closely-spaced extrusion tools.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the production of complex container shapes with defined wall thickness and geometry, optimizing the die gap profile for various container shapes, including asymmetrical designs, while maintaining production reliability and cost-effectiveness.
Implementation Method 1
elastically deformable sleeves, which form a wall section of the die gap and are elastically deformed during extrusion by a program-controlled power drive
Data Source
AI summary
The invention relates to a method for producing blow-molded hollow plastic bodies, in which tubular preforms (10) are simultaneously extruded from at least two adjacent extrusion dies (2) of a multi-extrusion head (1) and fed into blow mold cavities (4) of a clamping unit (3), in which the preforms (10) are expanded into hollow plastic bodies (13) by means of blown air after the blow mold cavities (4) have been closed. The preforms (10) emerge from a die gap (s) of the extrusion dies (2) which is defined by a mandrel (6) and a die body (3). The die gap width (s) of the extrusion dies (2) is changed during extrusion by positioning movements of the mandrels (6) and/or by positioning movements of the die bodies (7).The melt distribution of the preforms (10) exiting the extrusion dies (2) is modified circumferentially by deformation and/or displacement of an elastic sleeve (17) that defines the die gap (s) during extrusion. Each extrusion die (2) is assigned at least one program-controlled individual drive (18), which acts only on the elastically deformable sleeve (17) of the assigned extrusion die (2) by means of a transmission element (19). The transmission elements (19) engage in the area between adjacent extrusion dies (2) and are effective there on a circumferential section of the elastically deformable sleeve (17) assigned to the individual drive (18).